Vision is one of the most valued of human sensory experiences. Vision loss is an often feared untoward health event associated with serious medical, psychological, social, and financial consequences. The preservation of vision has thus been an important goal of health interventions and is recognized as such by the World Health Organization, the United States Congress, and the U.S. Centers for Disease Control. As reported in the Vision Preservation Act of 2008 in the United States Senate:                An estimated 80 million Americans have a potentially blinding eye disease;        19.1 million Americans report trouble seeing;        One million Americans are legally blind;        The number of Americans who are blind or visually impaired is expected to double by 2030;        It is estimated that blindness and visual impairment cost the Federal Government more than $4 billion annually in benefits and lost taxable income, and cost the United States economy approximately $51.4 billion annually in direct medical costs, direct nonmedical costs, and indirect costs such as lost productivity and wages;        Recognizing that the [United States government advocates] a public health approach to visual impairment, the Department of Health and Human Services dedicated a portion of its Healthy People 2010 initiative to vision. The initiative set out as a goal the improvement of . . . visual health through prevention, early detection, treatment, and rehabilitation.        
More specifically, vision loss can be caused by many factors, stemming from damage to all parts of the visual system. Retinal and optic nerve problems have emerged as leading causes of visual loss in developed countries. These posterior segment ophthalmic conditions are major and growing causes of vision loss globally, as well. Fortunately, many of these conditions, such as neovascular age-related macular degeneration, diabetic macular edema, proliferative diabetic retinopathy, retinal detachment, and glaucoma are treatable. In most of these cases, early diagnosis and proper follow up leads to adequate maintenance of visual function for life. Visualization of the retina and optic nerve by expert clinical readers is currently required to identify these pathologic changes, and the timely initiation of interventions for these back of the eye conditions is paramount to preserving vision. Furthermore, the early diagnosis of conditions such as dry age-related macular degeneration can help patients address risk factors for progression and thereby delay and possibly prevent long term visual loss. Generally, a retinal examination is performed by a trained clinician. The findings of the examination are then optimally documented through fundus photography.
There are number of various fundus cameras that are currently available on the market. For a summary of such cameras, one may refer to E. DeHoog and J. Schwiegerling, “Fundus camera systems: a comparative analysis,” Appl. Opt., 48, p. 221-228 (2009). For a summary of certain fundus cameras disclosed in the patent literature, one may refer to U.S. Patent Application Publication US 2008/0231803, “Compact Ocular Fundus Camera” of Feldon et al., the disclosure of which is incorporated herein by reference.
Bulky, expensive table-top fundus cameras are typically used to acquire high quality true-color and angiographic images of the retina with large fields of view. The operation of these table-top cameras is very elaborate, and requires a highly trained technician. A number of hand-held fundus cameras have also been developed in the past, including a contact type camera, the RetCam, sold by Clarity Medical Systems Inc. of Pleasanton, Calif., which is mainly used for infant ophthalmoscopy. These cameras, while having a smaller form-factor than the table-top devices, still lack the simplicity and portability of a device amenable to widespread distribution. The hand-held units in these cameras are bulky and are attached to a base-station via a thick cable. Alignment and focusing of the cameras is not intuitive, and in some versions the size of the field of view is inadequate. In addition, these cameras do not provide a significant reduction in cost, while lacking the imaging quality of the table-top cameras.
At this time, fundus photographic systems are typically available only in high-end, high-overhead technology dominated ophthalmic and optometric medical practices. Not all patients who could benefit from retinal fundus photography have access to it, even if they have a primary eye care provider. Likewise, those patients that rely on general practitioners, family practice physicians, internists, and pediatricians for ophthalmic health concerns have essentially no access to comprehensive retinal imaging. Moreover, special populations, including residents of nursing homes, assisted living facilities or group homes, prisoners, remote populations such as Native Americans on reservations and people residing in very rural communities have restricted access to a comprehensive and well documented fundus evaluation, and fundus imaging. The problem is even more severe in developing nations, and also in many Western countries where expensive heath care technology is more controlled, such as by government mandate.
It is further noted that rates of visual loss increase with age. Not surprisingly, ophthalmic screening programs have become increasingly important as the population ages in the United States and around the world. It was estimated by National Health Interview Survey (NHIS) that 9 million Americans 45 to 64 years of age had vision loss in 2006. As U.S. “baby boomers” age, the number of seniors at risk for vision loss will continue to grow. It has been documented that vision loss in this population results in decreased quality of life, increased healthcare costs, and increased risks of household accidents, including falls. Visual loss increases rapidly with age; over 25% of people are affected after age 74. Additionally, the American Academy of Ophthalmology recommends that people 65 or older should have a comprehensive eye examination every 1-2 years. Treatment, management, and prevention can effectively change the course of various conditions that result in visual loss, and oftentimes avoid blindness. Despite the proven benefits of ophthalmic evaluation, fewer than 10% of non-ophthalmologists or non-optometrists can effectively examine an eye using a direct ophthalmoscope. In addition, the direct ophthalmoscope has a very high magnification and small field of view, so that identifying disease processes may be problematic even to the trained practitioner. Furthermore, the traditional ophthalmoscope does not provide a way to record images, and thus, it is not possible to perform accurate follow up of disease progression over a period of time.
Glaucoma is treatable and can be diagnosed by identifying damage and signs of change of the optic nerve. Macular degeneration is treatable and can be identified by drusen, exudates, and hemorrhage in the macula. Diabetic retinopathy is treatable and can be diagnosed and followed by evaluating the optic disc, macula, and retinal vessels for multiple well described findings. Documenting changes over time in the eye is critical for proper diagnosis and treatment of all of these conditions.
Early detection and therapy of early eye diseases results in better vision for elderly patients. There has thus been increasing emphasis on ophthalmic imaging technologies as standards of care. Existing fundus cameras are expensive (e.g., $20,000 to $45,000 or more), require considerable technical expertise to operate, and are not easily portable. As a result, fundus photography as a screening tool has been implemented only to a very limited extent. The widespread implementation of fundus photography and usage in remote areas has so far not been practical. A low magnification, large field of view, user friendly, portable, cheap, and durable, fundus camera would be extremely beneficial in helping reduce rates of blindness. The benefits of a new method of photographic documentation of a patient's retina would be cost effectively expanded to large populations, thereby allowing for expert diagnosis, appropriate follow up, and optimal management to reach at-risk patients in all areas of our nation and the world.
In summary, there is therefore a need for a hand-held, durable, portable, and easy-to-use digital fundus low-cost camera, which can significantly improve patients' access to the high quality fundus images required to manage retinal and optic nerve diseases. The portability and versatility of such a device would enable the implementation of retinal imaging in large populations that previously did not have easy access to such technology.